Gymnema sylvestre appears to work by suppressing a desire for sugary foods as well as balancing blood sugar levels. On the diabetes front, the U.S. National Library of Medicine (NLM) and the National Institutes of Health (NIH) state that Gymnema sylvestre has "good scientific evidence" showing that it helps control blood sugar levels in people with type 1 and type 2 diabetes (when used in conjunction with insulin and other medications as prescribed by a doctor). One study in particular proves this out4. Twenty-two type-2 diabetics taking conventional oral diabetes medication were also given 400 mg of Gymnema a day for 18 to 20 months. Physiologically speaking, there does seem to be solid evidence that Gymnema sylvestre does lower cravings. The herb contains gymnemic acid,5 a nutrient found in certain plants that have been shown to suppress sweetness.